我想将数据从UISettingsViewController
传递到UIViewController
(主视图)。
我想做的是,当我在UISettingsViewController
中设置默认小费率时,UIViewController
中的值和小费率会发生变化,例如,如果我将默认小费率设置为10%,它会在主视图控制器中发生变化,并在我打开应用程序时设置为默认值。
我希望这是一个明确的解释,我来自另一个不会说英语的国家。
请查看我留下的图像,以便更好地了解我正在尝试做什么,我缝合图像两视图的视图主情节提要(用户界面)代码
import UIKit
class ViewController: UIViewController {
// Inputs
@IBOutlet weak var amountTextField: UITextField!
//Labels
@IBOutlet weak var TipPercentageLabel: UILabel!
@IBOutlet weak var numberOfPersonLabel: UILabel!
@IBOutlet weak var tipAmountLabel: UILabel!
@IBOutlet weak var totalBillLabel: UILabel!
@IBOutlet weak var billPerPersonLabel: UILabel!
//Slider & Stepper
@IBOutlet weak var tipSlider: UISlider!
@IBOutlet weak var personsStepper: UIStepper!
//Variables
var tipPercentage:Double = 0.20
var numberOfPerson:Int = 1
let numberFormatter:NSNumberFormatter = NSNumberFormatter()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
tipAmountLabel.text = "$0.00"
totalBillLabel.text = "Bill Total"
billPerPersonLabel.text = "$0.00"
TipPercentageLabel.text = "20.0%"
numberOfPersonLabel.text = "1"
self.amountTextField.becomeFirstResponder()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func setupContainer() {
tipSlider.minimumValue = 0
tipSlider.maximumValue = 100
tipSlider.value = 20
tipSlider.addTarget(self, action: "sliderTipChanged:", forControlEvents: .ValueChanged)
personsStepper.minimumValue = 1
personsStepper.maximumValue = 30
personsStepper.value = 1
personsStepper.addTarget(self, action: "sliderPersonChanged:", forControlEvents: .ValueChanged)
amountTextField.text = ""
refreshCalculation()
}
@IBAction func OnEditingFieldBill(sender: AnyObject) {
refreshCalculation()
}
func refreshCalculation() {
numberFormatter.numberStyle = NSNumberFormatterStyle.DecimalStyle
if let amount = numberFormatter.numberFromString(amountTextField.text!) as? Double {
let tipAmount = amount * tipPercentage
let totalBill = amount + tipAmount
let billPerPerson = totalBill / Double(numberOfPerson)
numberFormatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle
tipAmountLabel.text = numberFormatter.stringFromNumber(tipAmount)
totalBillLabel.text = numberFormatter.stringFromNumber(totalBill)
billPerPersonLabel.text = numberFormatter.stringFromNumber(billPerPerson)
} else {
tipAmountLabel.text = "-"
totalBillLabel.text = "-"
billPerPersonLabel.text = "-"
}
numberFormatter.numberStyle = NSNumberFormatterStyle.PercentStyle
numberFormatter.minimumFractionDigits = 1
numberFormatter.maximumFractionDigits = 1
TipPercentageLabel.text = self.numberFormatter.stringFromNumber(tipPercentage)
numberOfPersonLabel.text = "(numberOfPerson)"
}
@IBAction func sliderTipChanged(sender: UISlider) {
tipPercentage = Double(round(tipSlider.value)) / 100
refreshCalculation()
}
@IBAction func StepperPersonChanged(sender: UIStepper) {
numberOfPerson = Int(round(personsStepper.value))
refreshCalculation()
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
var DestViewController : SettingsViewController = segue.destinationViewController as! SettingsViewController
DestViewController =
}
}
最后一行说DestViewController =
的地方,是我不知道该做什么以及是否好的地方
第二视图控制器
import UIKit
class SettingsViewController: UIViewController {
@IBOutlet weak var tipControl: UISegmentedControl!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
@IBAction func DefaultRate(sender: AnyObject) {
var tipRate = [5, 10, 15, 2, 25, 30]
var tipRates = tipRate[tipControl.selectedSegmentIndex]
}
如果我理解正确,当您更改设置的默认速率时,您希望它能立即对主视图产生影响。因此,我建议您在设置中创建一个协议,并添加一个符合该协议的弱委托属性(将其设置为mainViewController)。然后,当设置中的速率发生变化时,会触发对代理的调用,从而导致mainViewController中的refreshCalculation。使用委托模式可以使2之间的意图和关系非常清晰且类型安全,但也可以防止2个视图控制器之间的保留循环。此外,您希望在加载mainViewController时设置默认值,因此在更改速率时也需要将速率保存在NSUserDefaults中。并使用0.20的备份从主视图初始化中的NSUserDefaults中读取它。
protocol SettingsDelegate {
func tipPercentageChanged(newValue : Double)
}
class SettingsVC : UIViewController {
var destName : String!
var delegate : SettingsDelegate?
@IBAction func segmentedValueChanged(sender : UISegmentedControl){
var tipRates = [0.05, 0.10, 0.15, 0.2, 0.25, 0.30]
let tipRate = tipRates[sender.selectedSegmentIndex]
delegate?.tipPercentageChanged(tipRate)
NSUserDefaults.standardUserDefaults().setDouble(tipRate, forKey: "DefaultTipRate")
NSUserDefaults.standardUserDefaults().synchronize()
}
}
class MainVC : UIViewController, SettingsDelegate {
var tipPercentage : Double = NSUserDefaults.standardUserDefaults().doubleForKey("DefaultTipRate") ?? 0.20
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if let settingsVC = segue.destinationViewController as? SettingsVC{
settingsVC.delegate = self
}
}
func tipPercentageChanged(newValue: Double) {
tipPercentage = newValue
refreshCalculation()
}
}
在控制器之间传递数据的方法是,要将数据提供给的控制器(在本例中为视图控制器)具有可以在segue源控制器(在此例中为设置视图控制器)中设置的公共属性。
我看到您的视图控制器有一个名为tipPercentage
的属性,所以我假设这是您想要设置的值。我还看到您有两个分段,一个从视图控制器到设置视图控制器,然后返回。请注意,在故事板中设置segue标识符是很重要的,即使您只有一个segue,它也可以保持代码的干净、可维护和无错误。如果您有多个segue,那么标识符将是必需的。
要设置标识符,请进入情节提要,单击片段本身,然后在右侧窗格中为其提供标识符。为了实现这段代码的目的,我将调用第一个"showSettings"和第二个<strong]"goBackToViewController">
你为赛格做准备的方式和你做的有点不同。你在ViewController末尾写的几行应该是:
override func prepareForSegue(segue: UIStoryboardSegue, sender:AnyObject?) {
if let id = segue.identifier { //identifier could be nil
if id == "showSettings" {
if let swv = segue.destination.destinationViewController as? SettingsViewController {
//Do any preparation here
}
}
}
}
现在,对于你真正感兴趣的片段,我们需要做一点准备。首先,您在函数中声明了tipRates
,因此永远无法从prepareFoeSegue访问它。相反,在类的顶部声明变量:
var tipRates:Double?
并像这样更改违约率:
@IBAction func DefaultRate(sender: AnyObject) {
var tipRate = [5, 10, 15, 2, 25, 30]
tipRates = Double(tipRate[tipControl.selectedSegmentIndex]) //We cast because tipRates is a double but tipRate an [Int]
}
既然我们可以访问类中的变量,我们就可以愉快地分段了。将以下代码放入设置视图控制器中:
override func prepareForSegue(segue: UIStoryboardSegue, sender:AnyObject?) {
if let id = segue.identifier { //identifier could be nil
if id == "goBackToViewController" {
if let vc = segue.destination.destinationViewController as? ViewController {
if let tip = tipRates {
vc.tipPercentage = tip/100 //We want the percentage
}
}
}
}
}
瞧!您的ViewController已获取信息。最后,请注意,当编译器能够弄清楚类型时,显式提及类型是不好的。例如var tipPercentage:Double = 0.20
应该是var tipPercentage = 0.20
当编译器仅通过查看值就知道它是双精度的。此外,考虑将应用程序嵌入UINavigationController中以便于导航。